End stop device for an electrically operated window screening arrangement

ABSTRACT

In an electrically operated window screening arrangement, where the movement in one direction between two end positions corresponding to a screened and an unscreened, respectively, window is effected by winding draw cords or strings (3, 4) on at least one winding drum (5, 6) in a horizontal main frame or sash member (7), the winding drum is connected by a motor shaft (8) with an electric drive motor (9). The movement in the opposite direction is carried out by a constant force during simultaneous unwinding of the draw cord or string (3, 4). An end stop device comprises a contact (11) for disruption of the motor current during movement in the opposite direction by activation from a sensor (17). The motor shaft (8) is journalled in such a way that it may perform a limited tilting movement at its connection with the drive motor (9), and the sensor comprises a contact member (17) belonging to the contact (11) and in abutment against a shaft part (8) positioned farthest away from the motor (9), the shaft (8) being spring-biassed in the opposite direction of the load produced by the draw cords or strings (3, 4).

BACKGROUND OF THE INVENTION

The invention concerns an end stop device for an electrically operatedwindow screening arrangement of the type whose movement in one directionbetween two end positions corresponding to a screened window and anunscreened window, respectively, is effected by winding draw cords orstrings connected with the screening arrangement on at least one windingdrum positioned in a horizontal main frame or sash member of the window,said drum being over a motor shaft connected with an electric drivemotor, whereas movement in the opposite direction is effected by meansof a constant force during simultaneous unwinding of said draw cord orstring from the winding drum, which end stop device comprises a contactfor disruption of the motor current during movement in said oppositedirection by activation from a sensor, the drive motor and said contactand sensor being positioned in or at said main frame or sash member.

DK publication no. 158 054 B discloses an electric drive mechanism for avenetian blind where the electric drive motor is provided on or builtinto the horizontal top section of the window sash. By hoisting thevenetian blind, the motor is disconnected when the bottom rail of thevenetian blind stops in the top position by detecting the motor currentand activating a reset circuit when the power exceeds a pre-determinedvalue.

For obtaining an end stop when lowering the venetian blind, thedisconnection of the power supply to the motor in this known design iseffected when the bottom rail reaches its bottom position in the waythat a reed contact mounted on the bottom section of the sash isaffected by a magnet positioned on the bottom rail of the venetianblind.

In addition to the practical inconvenience consisting in that anelectrical wire connection has to be established between the reedcontact at or in the sash bottom section and the motor arrangement inthe top section of the sash, it is in the known drive mechanism notpossible to bring the venetian blind to an automatic stop in the middleposition during lowering if the bottom rail meets an obstacle, eg. a potplant.

Furthermore, this known drive mechanism is not suited for other forms ofscreening devices as eg. roller blinds where it is the rolling downmovement which is motor-driven, whereas the rolling up movement iseffected by means of a constant spring force.

From DK publication no. 144 894 B, an electric operating device for avenetian blind is known where limit contacts for stopping the drivemotor at both upward and downward movement are mounted in the motorcasing built into the top list of the venetian blind, operating meansfor the contacts being journalled and guided in the motor casing andcomprising a pin which protrudes through the motor casing and functionsas an abutment for the bottom rail of the venetian blind in the topposition and to which a projecting sensor lever is fastened, said leveris affected by the draw cord or string of the venetian blind andactivates the contact when the cord or string are slackened at the stopof the bottom rail in the bottom position.

Although this embodiment represents a simplification as to installation,it requires a relatively complicated contact device and is aestheticallyless attractive due to the operating members projecting from the motorcasing.

SUMMARY OF THE INVENTION

The object of the invention is to provide a further simplified end stopdevice of the mentioned type where the drive motor and all parts of theend stop device may be built into the very same horizontal section ofthe window main frame or sash without projecting operating members, andwhere, in addition, the end stop device is suitable for all kinds ofwindow screening arrangements of the stated type such as venetianblinds, pleated blinds, roller shutters, roller blinds, insect screensetc.

For this purpose, the end stop device according to the invention ischaracterized in that the motor shaft is journalled in such a way thatin a plane substantially parallel with said moving directions, saidshaft may perform a limited tilting movement with axis of rotation in orat its connection with the drive motor between an active position forunrolling or rolling up and an inactive position, and that the sensorcomprises a contact member belonging to the contact and in abutmentagainst a shaft part situated at a distance from the motor, and theshaft is spring-biassed in the opposite direction of the load on theshaft effected by said draw cords or strings in order to act on theshaft towards said inactive position.

In the device according to the invention, the contact is actuated todisruption of the motor current, eg. by resetting commands to a motorcontrol circuit, and the spring-biassed contact member may tilt themotor shaft to the inactive position by slackening the draw cord orstring as the screening arrangement takes the end position in questionor meets some obstruction during its movement.

The device according to the invention is distinguished by an extremelysimple construction with few single parts which may all be built in ahidden manner into the top section or the bottom section of the windowmain frame or sash depending on the used form of screening device.

BRIEF DESCRIPTION OF THE DRAWING

In the following the invention is explained in detail under referencethe schematical drawing, in which

FIGS. 1 and 2 show a front and a side view, respectively, of anembodiment of a screening arrangement such as a pleated fold or avenetian blind, actuated by a downward power, e.g. the gravitationalforce, incorporating the end stop device according to the invention andshown in an intermediate position;

FIGS. 3 and 4 are front and side views corresponding to FIGS. 1 and 2,respectively, of the same embodiment, with the screening arrangement ina lowered end position corresponding to a screened window; and

FIG. 5 shows an embodiment of a spring-biassed screening arrangementsuch as a roller blind incorporating the end stop device of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the embodiment shown in FIGS. 1-4, a window screening arrangement inthe form of eg. a venetian blind or a pleated blind is schematicallyrepresented by a bottom rail 1 which, as shown in FIG. 3, in the fullylowered end position of the screening arrangement where the window isscreened, abuts against a lower horizontal main frame or sash member 2in the window. The screening arrangement 1 is suspended in draw cords orstrings 3 and 4 which in one end are fastened to the bottom rail 1 andin the opposite upper end are wound on winding drums 5 and 6 which arebuilt into an upper horizontal main frame or sash member schematicallyrepresented by its wall 7 facing downwards.

The winding drums 5 and 6 are via a common motor shaft 8 in drivingconnection with an electrical drive motor 9 also built into the mainframe or sash member 7.

In the shown embodiment, the lowering of the screening arrangement iseffected in the direction shown by the arrow 10 in FIG. 1 by a downwardforce which may in particular be the gravitational force perhapsassisted by a spring force or another force influence duringsimultaneous dewinding of the cords 3 and 4 from the drums 5 and 6whereas hoisting or raising of the screening device is carried outmerely by means of the motor 9 against said forces.

While the disruption of the motor current in fully hoisted position,where the bottom rail 1 is in abutment against the main frame or sashmember 7, may typically be effected by detection of the motor currentand activation of a reset circuit when exceeding a predetermined valuesuch as known per se, from before-mentioned DK publication no. 158 054B, the motor current is disrupted during lowering of the screeningarrangement towards the end position shown in FIG. 3 and where thebottom rail 1 abuts against the lower main frame or sash member 2, bymeans of an end stop device comprising a contact 11 eg. in the form of amicro-switch which via a cable connection 12 acts on a non-shown controlcircuit for the motor 9, which is supplied with power via a cableconnection 13.

When the bottom rail 1 reaches the end position shown in FIG. 3 inabutment against the lower main frame or sash member 2 or meets anotherobstacle, eg. a pot plant, during lowering of the screening arrangement,the contact 11 is activated by a sensor, member as explained in thefollowing, and thus interrupts the motor current.

The winding drums 5 and 6 and the motor shaft 8 are in the shownembodiment journalled in bearing brackets 14 and 15 which as shown inFIGS. 3 and 4 are designed with a slot 16 for the motor shaft 8.

The motor shaft 8 is according to the invention journalled in such a waythat in a plane substantially parallel with the moving direction forlowering and raising of the screening device, ie. the plane of thedrawing, it is permitted to perform a tilting movement through anangular range v about the connection of the motor shaft 8 with the drivemotor 9, said movement being limited by the extension of the slot 16.

The motor shaft 8 may thus be brought from the active position shown inFIG. 1 for dewinding and winding of the the draw cords 3 and 4 to theinactive position shown in FIG. 3. In the illustrated embodiment, thetilting movement is activated by engagement of a sensor member 17 actingon contact 11 against a part of the shaft 8 positioned at a distancefrom the motor 9, eg. at the bearing bracket 14 positioned farthest fromthe motor 9. In the shown embodiment, the sensor member 17 itself isspring-biassed to produce a spring force on the shaft 8 in the directionor arrow 17', i.e. opposite to the direction of the load acting on themotor shaft and originating from the draw cords 3 and 4. This springforce may, however, also be produced by a separate, perhaps adjustablespring positioned under the shaft 8.

When during lowering of the screening arrangement, the bottom rail 1comes to a stop against the lower main frame or sash member 2 or meetsanother obstruction, the cords 3 and 4 will be slackened so that theirload on the motor shaft 8 will be reduced or cease, whereby the motorshaft 8 is tilted to the position shown in FIG. 3 by the spring-biasacting on it, whereby the sensor member 17 will act on contract 11 todisrupt the motor current.

As shown in FIG. 5, the invention may also be applied in connection witha screening arrangement 18, eg. a roller blind or a roller shutter, ofthe type where a flexible screening breadth 19, eg. a roller blind clothor a set of slats in a roller shutter, is wound up on a spring-biassedroller 20 such that the rolling up movement is carried out by a constantspring force.

The rolling down is effected by means of an electrical drive devicepositioned in a lower main frame or sash member 22 which device inprinciple is designed in the same way as shown in FIGS. 1-4 with twowinding drums 25 and 26 for draw cords 23 and 24 which in the shownembodiment form one cord lead through the bottom rail 21 in order tosecure a parallelism. The drums 25 and 26 are over the motor shaft 28connected with the drive motor 29. The drums 25 and 26 and the motorshaft 28 are in the shown embodiment journalled in a common bearingbracket 30 with not-shown slots parallel with the direction of the cordforce for the motor shaft. The motor shaft may, by a spring-biassedcontact member 32 in the end stop contact 31 or another perhapsadjustable spring positioned under the shaft, be made to perform atilting movement in the same way as described above, however, in thiscase, by tightening the cords 23 and 24.

I claim:
 1. An end stop device for an electrically operated windowscreening arrangement, which is movable in a plane between two endpositions corresponding to a screened and an unscreened window,respectively, the movement of the screening arrangement towards one ofsaid end positions being effected by winding draw cords or strings (3,4; 23, 24) connected with the screening arrangement on at least onewinding drum (5, 6; 25, 26) positioned in a horizontal main frame orsash member (7, 22) of the window, said drum being connected via a motorshaft (8, 28) with an electric drive motor (9, 29), wherein movement ofthe screening arrangement towards the other end position is effected bya constant force during simultaneous unwinding of said draw cords orstrings (3, 4; 23, 24) from the winding drum (5, 6; 25, 26), said endstop device comprising a contact (11, 31) for disruption of the motorcurrent during movement towards said other end position in response toactivation from a sensor member (17, 32), the drive motor (9, 29), saidcontact (11) and said sensor member being arranged at said main frame orsash member (7, 22), characterized in that the motor shaft (8, 28) isjournalled in bearing members (14, 15) in a way to permit said shaft toperform a limited tilting movement in said plane about its connectionwith the drive motor (9, 29) between an active position for unwinding orwinding of said draw cords or strings and an inactive position, and thatsaid sensor member (17,32) is arranged to engage a part of said motorshaft (8,28) situated at a distance from the motor (9,29), said motorshaft (8, 28) being biassed by spring means in the direction towardssaid inactive position and opposite to the direction of the load on theshaft (8, 28) effected by said draw cords or strings (3, 4; 23, 24). 2.An end stop device according to claim 1, characterized in that saidspring means acts on said sensor member (17, 32).
 3. An end stop deviceaccording to claim 1, wherein the movement of said screening arrangementtowards the end position corresponding to a screened window is effectedby a downward force, characterized in that the winding drum (5, 6), thedrive motor (9) with accompanying motor shaft (8), said contact (11) andsaid sensor member (17) are arranged in an upper main frame or sashmember (7) for the window.
 4. An end stop device according to claim 1,wherein the movement of said screening arrangement towards the endposition corresponding to an unscreened window is effected by a springforce, characterized in that the winding drum (25, 26), the drive motor(29) with the motor shaft (28), said contact (31) and said sensor member(32) are arranged in a lower main frame or sash member (22) of thewindow.